table caption number non-automatic

[ck2136]

Hello @cardiomoon!

I've started using ztable and it's great! I think one of the things that could be useful is to have an option for captions to be automatically generated.

For example, when I use ztable with other latex outputting packages (e.g. xtable or stargazer), I think I'd rather have the captions be automatically generated and flow with the other tables created by other packages.

I'll try to work on this if I have some time. If you have any suggestions as to where I should look in the source code that would be great. Thanks!